No sign of insects. The leaves on the very bottom look ok, but 95 percent have fallen off. No new growth detected. Should I cut it down?
Most probably, the cold weather hit your holly pretty hard. You're not the only one. Deep snow apparently protected the lower part of the bush. You can cut back branches that are dead, but otherwise, give it a chance to recover at its own pace. Here's an article on holly pruning: https://www.gardeningknowhow.com/ornamental/shrubs/holly/trimming-holly-bushes-how-to-prune-holly-bushes.htm
Holly bush's leaves are turning brown and make the bush look dead.
Here is some information on holly problems: https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
Take a look at your plants to see if you can identify any of these factors. If not, most likely your holly is suffering the effects of the tough winter. You're not alone; we're hearing more reports of holly leaves browning than any other type of plant.
You can remove dead branches now, but if the branches are still flexible, leave them to recover in their own time. This article on holly pruning tells you more: https://www.gardeningknowhow.com/ornamental/shrubs/holly/trimming-holly-bushes-how-to-prune-holly-bushes.htm
My holly bush is dying. Leaves are falling off.
Start by checking for common diseases: https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
If you can eliminate these kinds of problems, chances are that the hard winter is what is causing your plant to lose leaves. Bend the branches to see if they are still alive; they will be flexible if they are, they will be crisp and snap in two if the branch is dead. You can cut off dead parts, and sit tight and hope for the best. Practice good care for your bushes, they will come back if they can. Here is an article on caring for hollies: https://www.gardeningknowhow.com/ornamental/shrubs/holly/growing-holly-bushes.htm
I live in Western PA. Every year my hollies get lots of berries in the spring, then fall off before they mature. This is happening now while they are tiny and green. How can I keep the berries from falling off? I have 3 groups in different areas of our yard... sun and sun/shade. They all have the same problem.
Oftentimes, this is due to poor pollination. If not properly pollinated, the berries will drop before they are fully mature. Lots of times changes in temperature, lots of rain, of a lack of pollinating insects are the cause. There is probably nothing that you can do for this year, but next year you need to take steps to make sure that the shrubs can be properly pollinated. These articles will offer suggestions for improving pollination: https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm, https://www.gardeningknowhow.com/garden-how-to/beneficial/creating-a-pollinator-garden.htm
I have noticed my only holly has suddenly began dropping its leaves. Is this OK during this hot spell? It is a young tree about 4 ft.
This indicates that it might not be getting enough water. Water the ground long and deeply 1-2 times a week rather than quick and shallowly everyday. Deep watering will make sure the water stays in the ground rather than evaporating from the top few inches.
The stems on my holly bushes are turning black. I can't seem to find out the cause or the solution to the problem.
It sounds like you have sooty mold. This article should help: https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm This is a fungus caused by the pests. I would treat the plant with neem oil. It is effective against the pests responsible as well as the sooty mold. Here is more information that may help you: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm
Last spring I had three cone shaped holly bushes planted. They did well all summer, fall and winter until recently. Our spring has been very wet and the leaves are turning yellow. I fed them in the early spring with Holly Tone. What do I do to save these bushes?
If you have had a lot of rain and the drainage in the area is not good, it can cause problems with leaves. Is the ground swampy? If the ground stays wet, the roots can't 'breathe' and falling leaves or yellowing would be a sign of this. Too much water causes iron chlorosis. This article will help you fix the problem: https://www.gardeningknowhow.com/ornamental/shrubs/holly/holly-yellow-leaves.htm